Effect of Storage Temperature on the Outgrowth and Toxin Production of Staphylococcus aureus in Freeze-Thawed Precooked Tuna Meat

2016 ◽  
Vol 79 (4) ◽  
pp. 620-627 ◽  
Author(s):  
AI KATAOKA ◽  
ELENA ENACHE ◽  
CARLA NAPIER ◽  
MELINDA HAYMAN ◽  
LISA WEDDIG
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Temperature ◽  
Salt Content ◽  
Frozen Storage ◽  
Toxin Production ◽  
Sensory Profile ◽  
Katsuwonus Pelamis ◽  
Enterotoxin Production ◽  
Sample Composition ◽  
Plate Counts

ABSTRACT The aim of this study was to determine the time for a 3-log CFU/g outgrowth of Staphylococcus aureus and its toxin production in previously frozen precooked tuna meat (albacore [Thunnus alalunga] prepared as loin, chunk, and flake or skipjack [Katsuwonus pelamis] prepared as chunk and flake) held either at 21 or 27°C. A five-strain cocktail of enterotoxin-producing S. aureus was surface inoculated with ~103 CFU/g onto tuna samples. The experimental time–temperature conditions were designed to mimic common industry holding conditions. After a 3-h incubation at 37°C, inoculated samples were individually vacuum sealed and stored at −20°C for 4 weeks. Following frozen storage, samples were thawed to the target temperature (21 or 27°C) and then incubated aerobically. Growth of S. aureus in tuna was then monitored using Baird Parker agar; simultaneously, aerobic plate counts, enterotoxin production, and sensory profile (color and odor) were determined. The results showed that the time for a 3-log CFU/g increase was >20 h at 21°C and 8 to 12 h at 27°C for albacore, with toxin production observed at 14 to 16 h at 21°C and at 8 h at 27°C. A 3-log CFU/g increase for skipjack occurred at 22 to 24 h at 21°C and at 10 to 14 h at 27°C. The toxin production in skipjack started at 20 to 22 h at 21°C and at 8 to 10 h at 27°C. Toxin production was observed before a 3-log increase was achieved in albacore samples at 21°C. Under all conditions, toxins were detected when the cell density of S. aureus was 6 log CFU/g. Overall, significantly faster S. aureus growth was observed in albacore compared with skipjack (P < 0.05), possibly owing to differences in sample composition (e.g., pH and salt content). The data developed from this study can be used by the tuna industry to model the growth and enterotoxin production of S. aureus and to design manufacturing controls that ensure food safety.

Survival and Growth of Staphylococcus aureus on Temperature-Abused Beef Livers

1984 ◽  
Vol 47 (4) ◽  
pp. 260-262 ◽  
Author(s):  
B. W. BERRY ◽  
K. F. LEDDY ◽  
C. A. ROTHENBERG
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Temperature ◽  
Frozen Storage ◽  
Storage Period ◽  
Developed Countries ◽  
Slow Surface ◽  
Plate Counts ◽  
Survival And Growth ◽  
High Storage ◽  
Storage Temperatures

Beef livers from freshly slaughtered cattle were inoculated with coagulase-positive Staphylococcus aureus and then placed in frozen storage. After 14 d of frozen storage, one-half of the livers were subjected to 21°C for 24 h followed by a 15-d period of storage at −1°C. The other livers were kept in frozen storage (−29°C) during this 15-d period after which all livers were subjected to either 10 or 21°C temperatures. S. aureus counts did not change during the 15-d storage period at −1°C, whereas aerobic plate counts (APC) increased by over 3 log10 cycles. The low storage temperature plus the growth of competitor bacteria most likely prevented S. aureus from proliferating. When all livers were subjected to 24 to 144 h of storage at either 10 or 21°C, those that had been subjected to 15 d of slow surface thawing displayed a lower S. aureus count and higher APC than livers subjected to rapid thawing followed by holding at the high temperatures. This may mean that if livers become contaminated with substantial numbers of S. aureus before freezing, then rapid thawing coupled with high storage temperatures (more typical of meat merchandising in less developed countries) could allow for rapid S. aureus growth before competitor organisms increase in numbers.

Modeling the Effect of Water Activity, pH, and Temperature on the Probability of Enterotoxin A Production by Staphylococcus aureus

2016 ◽  
Vol 79 (1) ◽  
pp. 148-152 ◽  
Author(s):  
TIAN DING ◽  
YAN-YAN YU ◽  
CHENG-AN HWANG ◽  
QING-LI DONG ◽  
SHI-GUO CHEN ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Water Activity ◽  
Storage Temperature ◽  
Probability Model ◽  
Toxin Production ◽  
Factors Affecting ◽  
Model Predictions ◽  
And Storage ◽  
Storage Temperatures ◽  
Good Agreement

ABSTRACT The objectives of this study were to develop a probability model of Staphylococcus aureus enterotoxin A (SEA) production as affected by water activity (aw), pH, and temperature in broth and assess its applicability for milk. The probability of SEA production was assessed in tryptic soy broth using 24 combinations of aw (0.86 to 0.99), pH (5.0 to 7.0), and storage temperature (10 to 30°C). The observed probabilities were fitted with a logistic regression to develop a probability model. The model had a concordant value of 97.5% and concordant index of 0.98, indicating that the model satisfactorily describes the probability of SEA production. The model showed that aw, pH, and temperature were significant factors affecting the probability of toxin production. The model predictions were in good agreement with the observed values obtained from milk. The model may help manufacturers in selecting product pH and aw and storage temperatures to prevent SEA production.

Effects of Potassium Sorbate on Normal Flora and on Staphylococcus aureus Added to Minced Cod

1982 ◽  
Vol 45 (9) ◽  
pp. 824-828 ◽  
Author(s):  
DONALD J. LYNCH ◽  
NORMAN N. POTTER
Keyword(s):  
Staphylococcus Aureus ◽  
Storage Period ◽  
Inhibitory Effect ◽  
Potassium Sorbate ◽  
Normal Flora ◽  
Ph Changes ◽  
Normal Microflora ◽  
Enterotoxin Production ◽  
Plate Counts ◽  
Storage Temperatures

Minced cod and pasteurized minced cod, with and without 0.5% potassium sorbate, were subjected to abusive storage temperatures of 7 and 15°C. Staphylococcus aureus FRI 100 was inoculated into the cod before storage. Total aerobic plate counts (20 and 35°C), pH changes, S. aureus counts and the presence of thermonuclease were monitored throughout the studies. With the unpasteurized minced cod, potassium sorbate caused slightly lower aerobic plate counts (at 20 and 35°C) in the 7°C study over an 11-day storage period. Psychrotrophic organisms were inhibited to a slightly greater extent than were mesophilic organisms. Inoculated S. aureus was quickly outgrown by the normal microflora without or with sorbate. Similar results were obtained at the still more abusive temperature of 15°C over a storage period of 5 d, but the inhibitory effect of sorbate was less evident. Pasteurized minced cod, inoculated with S. aureus and stored at 15°C, showed a considerable difference in growth of S. aureus with and without sorbate. Potassium sorbate resulted in a markedly slower rate of growth of the pathogen and a substantial delay of several days in production of detectable levels of thermonuclease. This delay in nuclease production is indicative of a similar delay in enterotoxin production.

Botulism Challenge Studies of a Modified Atmosphere Package for Fresh Mussels: Inoculated Pack Studies

2012 ◽  
Vol 75 (6) ◽  
pp. 1157-1166 ◽  
Author(s):  
C. R. NEWELL ◽  
LI MA ◽  
MICHAEL DOYLE
Keyword(s):  
Lactic Acid ◽  
Botulinum Toxin ◽  
Shelf Life ◽  
Storage Temperature ◽  
Modified Atmosphere Packaging ◽  
Toxin Production ◽  
Modified Atmosphere ◽  
Gas Composition ◽  
Plate Counts ◽  
Sampling Times

A series of botulism challenge studies were performed to determine the possibility of production of botulinum toxin in mussels (Mytilus edulis) held under a commercial high-oxygen (60 to 65% O2), modified atmosphere packaging (MAP) condition. Spore mixtures of six strains of nonproteolytic Clostridium botulinum were introduced into mussel MAP packages receiving different packaging buffers with or without the addition of lactic acid bacteria. Dye studies and package flipping trials were conducted to ensure internalization of spores by packed mussels. Inoculated mussel packages were stored at normal (4°C) and abusive (12°C) temperatures for 21 and 13 days, respectively, which were beyond the packaged mussels' intended shelf life. Microbiological and chemical analyses were conducted at predetermined intervals (a total of five sampling times at each temperature), including total aerobic plate counts, C. botulinum counts, lactic acid bacterial counts, package headspace gas composition, pH of packaging buffer and mussel meat, and botulinum toxin assays of packaging buffer and mussel meat. Results revealed that C. botulinum inoculated in fresh mussels packed under MAP packaging did not produce toxin, even at an abusive storage temperature and when held beyond their shelf life. No evidence was found that packaging buffers or gas composition influenced the lack of botulinum toxin production in packed mussels.

Microbial Counts on Surfaces of Lamb Carcasses and Shelf-Life of Refrigerated Ground Lamb

1982 ◽  
Vol 45 (11) ◽  
pp. 1013-1015 ◽  
Author(s):  
SAJIDA H. ALI ◽  
D. F. HOSHYARE ◽  
K. S. AL-DELAIMY
Keyword(s):  
Staphylococcus Aureus ◽  
Shelf Life ◽  
Microbial Growth ◽  
Storage Temperature ◽  
Fat Content ◽  
Refrigerated Storage ◽  
Average Surface ◽  
Microbial Counts ◽  
Plate Counts

Aerobic plate counts (APC) and counts on psychrotrophs, coliforms, Staphylococcus aureus and molds plus yeasts were made from the surface of fresh lamb carcasses and in ground lamb during refrigerated storage in Baghdad, Iraq. The average surface counts of carcasses sampled weekly over a 16-wk period were 1.1 × 106/cm2 and 2.6 × 104/cm2 for APC and psychrotrophs, respectively. The average ground lamb counts sampled weekly over a 5-wk period were 3.1 × 105/g and 1.2 × 105/g for APC and psychrotrophs, respectively. The average coliform, S. aureus and yeast plus mold counts were all between 103 and 104 CFU per cm2 or g for carcasses and ground lamb, respectively, on the day of slaughtering. Upon storage of the ground lamb at 2, 4, 5 and 6°C, both APC and psychrotroph counts increased to 109 CFU/g within 1 wk with more rapid microbial growth as the storage temperature increased from 2 to 6°C. Organoleptic spoilage was first detected when APC reached 109 CFU/g, or about 6 d at 5 to 6°C. The fat content of the ground lamb did not appreciably affect the APC and psychrotroph counts. Of 50 isolates of S. aureus, 48 were coagulase-positive.

Effect of Salt and Sodium Nitrite on Growth and Enterotoxin Production of Staphylococcus aureus during the Production of Air-Dried Fresh Pork Sausage†‡

2008 ◽  
Vol 71 (1) ◽  
pp. 191-195 ◽  
Author(s):  
W. BANG ◽  
D. J. HANSON ◽  
M. A. DRAKE
Keyword(s):  
Staphylococcus Aureus ◽  
Sodium Nitrite ◽  
Growth Characteristics ◽  
Coliform Bacteria ◽  
Safety Hazard ◽  
Pork Sausage ◽  
Enterotoxin Production ◽  
Plate Counts ◽  
Pork Sausages ◽  
Potential Food

Staphylococcus aureus contamination and enterotoxin production is a potential food safety hazard during the drying step of production of air-dried fresh country sausage. The growth characteristics and enterotoxin production of S. aureus during the drying step of this product with and without added sodium nitrite were evaluated. Three strains of S. aureus were grown to stationary phase and inoculated (104 CFU/g) into sausage ingredients. Fresh pork sausages were stuffed into natural casings and allowed to dry for 10 days at 21°C with 60% relative humidity (RH). In control sausage (1.76% [wt/wt] salt) with no S. aureus, aerobic plate counts increased by 5.5 log/g during the 10-day drying period, and coliforms increased by 4.8 log/g. The addition of sodium nitrite (154 ppm of nitrite, 2.24% [wt/wt] salt) or increased salt (3.64%, wt/wt) to sausage limited the growth of coliform bacteria (P < 0.05). S. aureus numbers increased approximately 2 log units during the drying step, regardless of additional salt or nitrite. Additional salt or nitrite had no effect on S. aureus growth (P > 0.05). Staphylococcal enterotoxin (SE) was not detected in air-dried fresh sausages at any time. Our results suggest that drying of fresh pork sausage under similar parameters listed in this study does not support SE production.

Staphylococcus aureus Growth and Toxin Production in Nitrogen-Packed Sandwiches1

1982 ◽  
Vol 45 (2) ◽  
pp. 157-161 ◽  
Author(s):  
R. W. BENNETT ◽  
W. T. AMOS
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Toxin Production ◽  
Food Storage ◽  
Potential Hazard ◽  
Enterotoxin Production

Plastic-enclosed sausage, hamburger and turkey sandwiches were inoculated with enterotoxigenic Staphylococcus aureus to evaluate the potential hazard of staphylococcal food poisoning in sealed foods maintained in an N2 environment. The effect of such food storage on staphylococcal growth and enterotoxin production was determined under varying conditions of time (1–31 days) and temperature (8, 12, and 26 C). At 8 and 12 C, none of the sandwiches became toxic after 31 days of storage; however, at 26 C, sausage and hamburger sandwiches became toxic at days 2 and 4, respectively, while remaining organoleptically acceptable. Turkey sandwiches did not support sufficient growth of staphylococci to allow the production of detectable amounts of enterotoxin at any of the temperatures tested.

A Probability Model for Enterotoxin Production of Bacillus cereus as a Function of pH and Temperature

2013 ◽  
Vol 76 (2) ◽  
pp. 343-347 ◽  
Author(s):  
TIAN DING ◽  
JUN WANG ◽  
MYOUNG-SU PARK ◽  
CHENG-AN HWANG ◽  
DEOG-HWAN OH
Keyword(s):  
Bacillus Cereus ◽  
Storage Temperature ◽  
Probability Model ◽  
Food Poisoning ◽  
Toxin Production ◽  
Severe Nausea ◽  
Enterotoxin Production ◽  
Test Kit ◽  
And Storage ◽  
Selection Of

Bacillus cereus is frequently isolated from a variety of foods, including vegetables, dairy products, meats, and other raw and processed foods. The bacterium is capable of producing an enterotoxin and emetic toxin that can cause severe nausea, vomiting, and diarrhea. The objectives of this study were to assess and model the probability of enterotoxin production of B. cereus in a broth model as affected by the broth pH and storage temperature. A three-strain mixture of B. cereus was inoculated in tryptic soy broth adjusted to pH 5.0, 6.0, 7.2, 8.0, and 8.5, and the samples were stored at 15, 20, 25, 30, and 35°C for 24 h. A total of 25 combinations of pH and temperature, each with 10 samples, were tested. The presence of enterotoxin in broth was assayed using a commercial test kit. The probabilities of positive enterotoxin production in 25 treatments were fitted with a logistic regression to develop a probability model to describe the probability of toxin production as a function of pH and temperature. The resulting model showed that the probabilities of enterotoxin production of B. cereus in broth increased as the temperature increased and/or as the broth pH approached 7.0. The model described the experimental data satisfactorily and identified the boundary of pH and temperature for the production of enterotoxin. The model could provide information for assessing the food poisoning risk associated with enterotoxins of B. cereus and for the selection of product pH and storage temperature for foods to reduce the hazards associated with B. cereus.

Microbiological Quality of Fresh Blue Crabmeat, Clams and Oysters

1983 ◽  
Vol 46 (11) ◽  
pp. 978-981 ◽  
Author(s):  
B. A. WENTZ ◽  
A. P. DURAN ◽  
A. SWARTZENTRUBER ◽  
A. H. SCHWAB ◽  
R. B. READ
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Geometric Means ◽  
Colony Forming Units ◽  
Plate Counts ◽  
The Mean ◽  
Eastern Oysters

The microbiological quality of fresh blue crabmeat, soft- and hardshell clams and shucked Eastern oysters was determined at the retail (crabmeat, oysters) and wholesale (clams) levels. Geometric means of aerobic plate counts incubated at 35°C were: blue crabmeat 140,000 colony-forming units (CFU)/g, hardshell clams, 950 CFU/g, softshell clams 680 CFU/g and shucked Eastern oysters 390,000 CFU/g. Coliform geometric means ranged from 3,6/100 g for hardshell clams to 21/g for blue crabmeat. Means for fecal coliforms or Escherichia coli ranged from <3/100 g for clams to 27/100 g for oysters, The mean Staphylococcus aureus count in blue crabmeat was 10/g.

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